michael@0: 
michael@0: /*
michael@0:  * Copyright 2006 The Android Open Source Project
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: 
michael@0: #include "SkScan.h"
michael@0: #include "SkBlitter.h"
michael@0: #include "SkRasterClip.h"
michael@0: #include "SkFDot6.h"
michael@0: #include "SkLineClipper.h"
michael@0: 
michael@0: static void horiline(int x, int stopx, SkFixed fy, SkFixed dy,
michael@0:                      SkBlitter* blitter) {
michael@0:     SkASSERT(x < stopx);
michael@0: 
michael@0:     do {
michael@0:         blitter->blitH(x, fy >> 16, 1);
michael@0:         fy += dy;
michael@0:     } while (++x < stopx);
michael@0: }
michael@0: 
michael@0: static void vertline(int y, int stopy, SkFixed fx, SkFixed dx,
michael@0:                      SkBlitter* blitter) {
michael@0:     SkASSERT(y < stopy);
michael@0: 
michael@0:     do {
michael@0:         blitter->blitH(fx >> 16, y, 1);
michael@0:         fx += dx;
michael@0:     } while (++y < stopy);
michael@0: }
michael@0: 
michael@0: #ifdef SK_DEBUG
michael@0: static bool canConvertFDot6ToFixed(SkFDot6 x) {
michael@0:     const int maxDot6 = SK_MaxS32 >> (16 - 6);
michael@0:     return SkAbs32(x) <= maxDot6;
michael@0: }
michael@0: #endif
michael@0: 
michael@0: void SkScan::HairLineRgn(const SkPoint& pt0, const SkPoint& pt1,
michael@0:                          const SkRegion* clip, SkBlitter* blitter) {
michael@0:     SkBlitterClipper    clipper;
michael@0:     SkRect  r;
michael@0:     SkIRect clipR, ptsR;
michael@0:     SkPoint pts[2] = { pt0, pt1 };
michael@0: 
michael@0:     // We have to pre-clip the line to fit in a SkFixed, so we just chop
michael@0:     // the line. TODO find a way to actually draw beyond that range.
michael@0:     {
michael@0:         SkRect fixedBounds;
michael@0:         const SkScalar max = SkIntToScalar(32767);
michael@0:         fixedBounds.set(-max, -max, max, max);
michael@0:         if (!SkLineClipper::IntersectLine(pts, fixedBounds, pts)) {
michael@0:             return;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     if (clip) {
michael@0:         // Perform a clip in scalar space, so we catch huge values which might
michael@0:         // be missed after we convert to SkFDot6 (overflow)
michael@0:         r.set(clip->getBounds());
michael@0:         if (!SkLineClipper::IntersectLine(pts, r, pts)) {
michael@0:             return;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     SkFDot6 x0 = SkScalarToFDot6(pts[0].fX);
michael@0:     SkFDot6 y0 = SkScalarToFDot6(pts[0].fY);
michael@0:     SkFDot6 x1 = SkScalarToFDot6(pts[1].fX);
michael@0:     SkFDot6 y1 = SkScalarToFDot6(pts[1].fY);
michael@0: 
michael@0:     SkASSERT(canConvertFDot6ToFixed(x0));
michael@0:     SkASSERT(canConvertFDot6ToFixed(y0));
michael@0:     SkASSERT(canConvertFDot6ToFixed(x1));
michael@0:     SkASSERT(canConvertFDot6ToFixed(y1));
michael@0: 
michael@0:     if (clip) {
michael@0:         // now perform clipping again, as the rounding to dot6 can wiggle us
michael@0:         // our rects are really dot6 rects, but since we've already used
michael@0:         // lineclipper, we know they will fit in 32bits (26.6)
michael@0:         const SkIRect& bounds = clip->getBounds();
michael@0: 
michael@0:         clipR.set(SkIntToFDot6(bounds.fLeft), SkIntToFDot6(bounds.fTop),
michael@0:                   SkIntToFDot6(bounds.fRight), SkIntToFDot6(bounds.fBottom));
michael@0:         ptsR.set(x0, y0, x1, y1);
michael@0:         ptsR.sort();
michael@0: 
michael@0:         // outset the right and bottom, to account for how hairlines are
michael@0:         // actually drawn, which may hit the pixel to the right or below of
michael@0:         // the coordinate
michael@0:         ptsR.fRight += SK_FDot6One;
michael@0:         ptsR.fBottom += SK_FDot6One;
michael@0: 
michael@0:         if (!SkIRect::Intersects(ptsR, clipR)) {
michael@0:             return;
michael@0:         }
michael@0:         if (clip->isRect() && clipR.contains(ptsR)) {
michael@0:             clip = NULL;
michael@0:         } else {
michael@0:             blitter = clipper.apply(blitter, clip);
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     SkFDot6 dx = x1 - x0;
michael@0:     SkFDot6 dy = y1 - y0;
michael@0: 
michael@0:     if (SkAbs32(dx) > SkAbs32(dy)) { // mostly horizontal
michael@0:         if (x0 > x1) {   // we want to go left-to-right
michael@0:             SkTSwap<SkFDot6>(x0, x1);
michael@0:             SkTSwap<SkFDot6>(y0, y1);
michael@0:         }
michael@0:         int ix0 = SkFDot6Round(x0);
michael@0:         int ix1 = SkFDot6Round(x1);
michael@0:         if (ix0 == ix1) {// too short to draw
michael@0:             return;
michael@0:         }
michael@0: 
michael@0:         SkFixed slope = SkFixedDiv(dy, dx);
michael@0:         SkFixed startY = SkFDot6ToFixed(y0) + (slope * ((32 - x0) & 63) >> 6);
michael@0: 
michael@0:         horiline(ix0, ix1, startY, slope, blitter);
michael@0:     } else {              // mostly vertical
michael@0:         if (y0 > y1) {   // we want to go top-to-bottom
michael@0:             SkTSwap<SkFDot6>(x0, x1);
michael@0:             SkTSwap<SkFDot6>(y0, y1);
michael@0:         }
michael@0:         int iy0 = SkFDot6Round(y0);
michael@0:         int iy1 = SkFDot6Round(y1);
michael@0:         if (iy0 == iy1) { // too short to draw
michael@0:             return;
michael@0:         }
michael@0: 
michael@0:         SkFixed slope = SkFixedDiv(dx, dy);
michael@0:         SkFixed startX = SkFDot6ToFixed(x0) + (slope * ((32 - y0) & 63) >> 6);
michael@0: 
michael@0:         vertline(iy0, iy1, startX, slope, blitter);
michael@0:     }
michael@0: }
michael@0: 
michael@0: // we don't just draw 4 lines, 'cause that can leave a gap in the bottom-right
michael@0: // and double-hit the top-left.
michael@0: // TODO: handle huge coordinates on rect (before calling SkScalarToFixed)
michael@0: void SkScan::HairRect(const SkRect& rect, const SkRasterClip& clip,
michael@0:                       SkBlitter* blitter) {
michael@0:     SkAAClipBlitterWrapper wrapper;
michael@0:     SkBlitterClipper    clipper;
michael@0:     SkIRect             r;
michael@0: 
michael@0:     r.set(SkScalarToFixed(rect.fLeft) >> 16,
michael@0:           SkScalarToFixed(rect.fTop) >> 16,
michael@0:           (SkScalarToFixed(rect.fRight) >> 16) + 1,
michael@0:           (SkScalarToFixed(rect.fBottom) >> 16) + 1);
michael@0: 
michael@0:     if (clip.quickReject(r)) {
michael@0:         return;
michael@0:     }
michael@0:     if (!clip.quickContains(r)) {
michael@0:         const SkRegion* clipRgn;
michael@0:         if (clip.isBW()) {
michael@0:             clipRgn = &clip.bwRgn();
michael@0:         } else {
michael@0:             wrapper.init(clip, blitter);
michael@0:             clipRgn = &wrapper.getRgn();
michael@0:             blitter = wrapper.getBlitter();
michael@0:         }
michael@0:         blitter = clipper.apply(blitter, clipRgn);
michael@0:     }
michael@0: 
michael@0:     int width = r.width();
michael@0:     int height = r.height();
michael@0: 
michael@0:     if ((width | height) == 0) {
michael@0:         return;
michael@0:     }
michael@0:     if (width <= 2 || height <= 2) {
michael@0:         blitter->blitRect(r.fLeft, r.fTop, width, height);
michael@0:         return;
michael@0:     }
michael@0:     // if we get here, we know we have 4 segments to draw
michael@0:     blitter->blitH(r.fLeft, r.fTop, width);                     // top
michael@0:     blitter->blitRect(r.fLeft, r.fTop + 1, 1, height - 2);      // left
michael@0:     blitter->blitRect(r.fRight - 1, r.fTop + 1, 1, height - 2); // right
michael@0:     blitter->blitH(r.fLeft, r.fBottom - 1, width);              // bottom
michael@0: }
michael@0: 
michael@0: ///////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: #include "SkPath.h"
michael@0: #include "SkGeometry.h"
michael@0: 
michael@0: static int compute_int_quad_dist(const SkPoint pts[3]) {
michael@0:     // compute the vector between the control point ([1]) and the middle of the
michael@0:     // line connecting the start and end ([0] and [2])
michael@0:     SkScalar dx = SkScalarHalf(pts[0].fX + pts[2].fX) - pts[1].fX;
michael@0:     SkScalar dy = SkScalarHalf(pts[0].fY + pts[2].fY) - pts[1].fY;
michael@0:     // we want everyone to be positive
michael@0:     dx = SkScalarAbs(dx);
michael@0:     dy = SkScalarAbs(dy);
michael@0:     // convert to whole pixel values (use ceiling to be conservative)
michael@0:     int idx = SkScalarCeilToInt(dx);
michael@0:     int idy = SkScalarCeilToInt(dy);
michael@0:     // use the cheap approx for distance
michael@0:     if (idx > idy) {
michael@0:         return idx + (idy >> 1);
michael@0:     } else {
michael@0:         return idy + (idx >> 1);
michael@0:     }
michael@0: }
michael@0: 
michael@0: typedef void (*LineProc)(const SkPoint&, const SkPoint&, const SkRegion*,
michael@0:                          SkBlitter*);
michael@0: 
michael@0: static void hairquad(const SkPoint pts[3], const SkRegion* clip,
michael@0:                      SkBlitter* blitter, int level, LineProc lineproc) {
michael@0:     if (level > 0) {
michael@0:         SkPoint tmp[5];
michael@0: 
michael@0:         SkChopQuadAtHalf(pts, tmp);
michael@0:         hairquad(tmp, clip, blitter, level - 1, lineproc);
michael@0:         hairquad(&tmp[2], clip, blitter, level - 1, lineproc);
michael@0:     } else {
michael@0:         lineproc(pts[0], pts[2], clip, blitter);
michael@0:     }
michael@0: }
michael@0: 
michael@0: static void haircubic(const SkPoint pts[4], const SkRegion* clip,
michael@0:                       SkBlitter* blitter, int level, LineProc lineproc) {
michael@0:     if (level > 0) {
michael@0:         SkPoint tmp[7];
michael@0: 
michael@0:         SkChopCubicAt(pts, tmp, SK_Scalar1/2);
michael@0:         haircubic(tmp, clip, blitter, level - 1, lineproc);
michael@0:         haircubic(&tmp[3], clip, blitter, level - 1, lineproc);
michael@0:     } else {
michael@0:         lineproc(pts[0], pts[3], clip, blitter);
michael@0:     }
michael@0: }
michael@0: 
michael@0: #define kMaxCubicSubdivideLevel 6
michael@0: #define kMaxQuadSubdivideLevel  5
michael@0: 
michael@0: static int compute_quad_level(const SkPoint pts[3]) {
michael@0:     int d = compute_int_quad_dist(pts);
michael@0:     /*  quadratics approach the line connecting their start and end points
michael@0:      4x closer with each subdivision, so we compute the number of
michael@0:      subdivisions to be the minimum need to get that distance to be less
michael@0:      than a pixel.
michael@0:      */
michael@0:     int level = (33 - SkCLZ(d)) >> 1;
michael@0:     // sanity check on level (from the previous version)
michael@0:     if (level > kMaxQuadSubdivideLevel) {
michael@0:         level = kMaxQuadSubdivideLevel;
michael@0:     }
michael@0:     return level;
michael@0: }
michael@0: 
michael@0: static void hair_path(const SkPath& path, const SkRasterClip& rclip,
michael@0:                       SkBlitter* blitter, LineProc lineproc) {
michael@0:     if (path.isEmpty()) {
michael@0:         return;
michael@0:     }
michael@0: 
michael@0:     SkAAClipBlitterWrapper wrap;
michael@0:     const SkRegion* clip = NULL;
michael@0: 
michael@0:     {
michael@0:         SkIRect ibounds;
michael@0:         path.getBounds().roundOut(&ibounds);
michael@0:         ibounds.inset(-1, -1);
michael@0: 
michael@0:         if (rclip.quickReject(ibounds)) {
michael@0:             return;
michael@0:         }
michael@0:         if (!rclip.quickContains(ibounds)) {
michael@0:             if (rclip.isBW()) {
michael@0:                 clip = &rclip.bwRgn();
michael@0:             } else {
michael@0:                 wrap.init(rclip, blitter);
michael@0:                 blitter = wrap.getBlitter();
michael@0:                 clip = &wrap.getRgn();
michael@0:             }
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     SkPath::Iter    iter(path, false);
michael@0:     SkPoint         pts[4];
michael@0:     SkPath::Verb    verb;
michael@0:     SkAutoConicToQuads converter;
michael@0: 
michael@0:     while ((verb = iter.next(pts, false)) != SkPath::kDone_Verb) {
michael@0:         switch (verb) {
michael@0:             case SkPath::kMove_Verb:
michael@0:                 break;
michael@0:             case SkPath::kLine_Verb:
michael@0:                 lineproc(pts[0], pts[1], clip, blitter);
michael@0:                 break;
michael@0:             case SkPath::kQuad_Verb:
michael@0:                 hairquad(pts, clip, blitter, compute_quad_level(pts), lineproc);
michael@0:                 break;
michael@0:             case SkPath::kConic_Verb: {
michael@0:                 // how close should the quads be to the original conic?
michael@0:                 const SkScalar tol = SK_Scalar1 / 4;
michael@0:                 const SkPoint* quadPts = converter.computeQuads(pts,
michael@0:                                                        iter.conicWeight(), tol);
michael@0:                 for (int i = 0; i < converter.countQuads(); ++i) {
michael@0:                     int level = compute_quad_level(quadPts);
michael@0:                     hairquad(quadPts, clip, blitter, level, lineproc);
michael@0:                     quadPts += 2;
michael@0:                 }
michael@0:                 break;
michael@0:             }
michael@0:             case SkPath::kCubic_Verb:
michael@0:                 haircubic(pts, clip, blitter, kMaxCubicSubdivideLevel, lineproc);
michael@0:                 break;
michael@0:             case SkPath::kClose_Verb:
michael@0:                 break;
michael@0:             case SkPath::kDone_Verb:
michael@0:                 break;
michael@0:         }
michael@0:     }
michael@0: }
michael@0: 
michael@0: void SkScan::HairPath(const SkPath& path, const SkRasterClip& clip,
michael@0:                       SkBlitter* blitter) {
michael@0:     hair_path(path, clip, blitter, SkScan::HairLineRgn);
michael@0: }
michael@0: 
michael@0: void SkScan::AntiHairPath(const SkPath& path, const SkRasterClip& clip,
michael@0:                           SkBlitter* blitter) {
michael@0:     hair_path(path, clip, blitter, SkScan::AntiHairLineRgn);
michael@0: }
michael@0: 
michael@0: ///////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: void SkScan::FrameRect(const SkRect& r, const SkPoint& strokeSize,
michael@0:                        const SkRasterClip& clip, SkBlitter* blitter) {
michael@0:     SkASSERT(strokeSize.fX >= 0 && strokeSize.fY >= 0);
michael@0: 
michael@0:     if (strokeSize.fX < 0 || strokeSize.fY < 0) {
michael@0:         return;
michael@0:     }
michael@0: 
michael@0:     const SkScalar dx = strokeSize.fX;
michael@0:     const SkScalar dy = strokeSize.fY;
michael@0:     SkScalar rx = SkScalarHalf(dx);
michael@0:     SkScalar ry = SkScalarHalf(dy);
michael@0:     SkRect   outer, tmp;
michael@0: 
michael@0:     outer.set(r.fLeft - rx, r.fTop - ry,
michael@0:                 r.fRight + rx, r.fBottom + ry);
michael@0: 
michael@0:     if (r.width() <= dx || r.height() <= dx) {
michael@0:         SkScan::FillRect(outer, clip, blitter);
michael@0:         return;
michael@0:     }
michael@0: 
michael@0:     tmp.set(outer.fLeft, outer.fTop, outer.fRight, outer.fTop + dy);
michael@0:     SkScan::FillRect(tmp, clip, blitter);
michael@0:     tmp.fTop = outer.fBottom - dy;
michael@0:     tmp.fBottom = outer.fBottom;
michael@0:     SkScan::FillRect(tmp, clip, blitter);
michael@0: 
michael@0:     tmp.set(outer.fLeft, outer.fTop + dy, outer.fLeft + dx, outer.fBottom - dy);
michael@0:     SkScan::FillRect(tmp, clip, blitter);
michael@0:     tmp.fLeft = outer.fRight - dx;
michael@0:     tmp.fRight = outer.fRight;
michael@0:     SkScan::FillRect(tmp, clip, blitter);
michael@0: }
michael@0: 
michael@0: void SkScan::HairLine(const SkPoint& p0, const SkPoint& p1,
michael@0:                       const SkRasterClip& clip, SkBlitter* blitter) {
michael@0:     if (clip.isBW()) {
michael@0:         HairLineRgn(p0, p1, &clip.bwRgn(), blitter);
michael@0:     } else {
michael@0:         const SkRegion* clipRgn = NULL;
michael@0:         SkRect r;
michael@0:         SkIRect ir;
michael@0:         r.set(p0.fX, p0.fY, p1.fX, p1.fY);
michael@0:         r.sort();
michael@0:         r.inset(-SK_ScalarHalf, -SK_ScalarHalf);
michael@0:         r.roundOut(&ir);
michael@0: 
michael@0:         SkAAClipBlitterWrapper wrap;
michael@0:         if (!clip.quickContains(ir)) {
michael@0:             wrap.init(clip, blitter);
michael@0:             blitter = wrap.getBlitter();
michael@0:             clipRgn = &wrap.getRgn();
michael@0:         }
michael@0:         HairLineRgn(p0, p1, clipRgn, blitter);
michael@0:     }
michael@0: }
michael@0: 
michael@0: void SkScan::AntiHairLine(const SkPoint& p0, const SkPoint& p1,
michael@0:                           const SkRasterClip& clip, SkBlitter* blitter) {
michael@0:     if (clip.isBW()) {
michael@0:         AntiHairLineRgn(p0, p1, &clip.bwRgn(), blitter);
michael@0:     } else {
michael@0:         const SkRegion* clipRgn = NULL;
michael@0:         SkRect r;
michael@0:         SkIRect ir;
michael@0:         r.set(p0.fX, p0.fY, p1.fX, p1.fY);
michael@0:         r.sort();
michael@0:         r.roundOut(&ir);
michael@0:         ir.inset(-1, -1);
michael@0: 
michael@0:         SkAAClipBlitterWrapper wrap;
michael@0:         if (!clip.quickContains(ir)) {
michael@0:             wrap.init(clip, blitter);
michael@0:             blitter = wrap.getBlitter();
michael@0:             clipRgn = &wrap.getRgn();
michael@0:         }
michael@0:         AntiHairLineRgn(p0, p1, clipRgn, blitter);
michael@0:     }
michael@0: }